A growing number of US companies have cut ties with the National Rifle Association (NRA) as the gun lobby comes under immense criticism following the last week's mass shooting at a Florida high school.

Several car rental companies, hotels and banks have cancelled the special offers and discounts they have for NRA members.

The moves come amid widespread calls to boycott companies and groups that have ties to the powerful pro-gun group.

At least 17 people were killed last week when a gunman opened fire on students and teachers at the Marjory Stoneman Douglas High School in Parkland, Florida. According to police, 19-year-old Nikolas Cruz confessed to carrying out the shooting. He allegedly used an AR-15-style semiautomatic rifle.

Since the shooting, students and their families have organised near-daily protests, demanding gun control reform. Online, the #BoycottNRA campaign has gained momentum, with many pledging to stop doing business with companies that have ties to the NRA.

Under pressure, more than a dozen companies - including car rental giants Hertz and Budget, First National Bank and MetLife insurance - have ended their relationships with the NRA, according to progressive news site ThinkProgess.

First National Bank of Omaha, the largest privately held bank in the United States, said it would not renew its contract with the NRA. As a result, the bank will stop issuing NRA credit cards.

Customer feedback has caused us to review our relationship with the NRA. As a result, First National Bank of Omaha will not renew its contract with the National Rifle Association to issue the NRA Visa Card.

This week, NRA Executive Vice President Wayne LaPierre called on "every citizen who loves this country and treasures its freedom to stand and unflinchingly defend the Second Amendment, the one freedom that protects us all."

"I call on every citizen who loves this country and treasures its freedom tostand and unflinchingly defend the Second Amendment, the one freedomthat protects us all." - Wayne LaPierre @CPAC

"So this crazy man, who walked in, wouldn't even know who it is that has it," he added. "That's good. That's not bad. That's good. And the teacher would have shot the hell out of him before he knew what happened."

On Friday, the investigation into the shooting revealed that an armed deputy was present at Marjory Stoneman Douglas High School during the incident. According to Sheriff Scott Israel, the deputy waited outside the school for nearly four minutes while the shooting took place. That deputy has since resigned.